My thoughts and reminders as GIS Librarian at the University of Texas at Arlington. This blog is primarily a way for me to jot down my ideas and also to record notes from other blogs and feeds out there. Everyone is welcome to follow along if you like.

Thursday, October 25, 2007

This has been a whirlwind frantic rush to pull together but just about everything is ready to go for this afternoon's GIS workshop. Should be a great one...

Dr. Melanie Sattler, Civil & Environmental Engineering professor, will lead the workshop with a 30 minute discussion of why air pollution is important in the D/FW Metroplex and discuss the various campus research efforts to study and model air quality.

I will then lead everyone though a hands-on GIS exercise that will include the following steps:

Calculate total pounds of air emissions within 5 miles of everyone's home address (using spatial join)

Friday, October 05, 2007

Helped an engineering student yesterday to display a table with over 500,000 XY coordinates and convert it to a shapefile. The table the student brought was a 2.5 gig CSV file. It gave me some unexpected troubles.

The conclusion is that the manipulation of large tables is often times best done using Microsoft Access. Specifically, converting field types for large tables with hundreds of thousands of records is best done in Microsoft Access, and not in ArcMap.

If you are interested in the particulars, read on below.

Brought the table into ArcMap, but every field in the table was read by ArcMap as a text field. Opened the table in ArcMap, and all the values were numerical coordinates. Opened the table in Excel, and of course the table only partially opened as there were too many records. The portion of the table that did open were all numerical coordinates, but Excel was also reading the fields as text. No problem. Switched back over to ArcMap and attempted to add two new double fields and use the field calculator to copy the text fields into the double fields. ArcMap is unable to add fields to text files, so we had to export the table as a DBF first. This took over 5 minutes as there was so much data. Every time we tried to add a new double field to the large DBF file, the screen would turn white and would hang there indefinitely. We tried this twice, and gave up on each attempt after 5 minutes of inactivity.

Then I had the idea to import the table into a blank Microsoft Access database where I can directly change the field types from text to double. Before changing the field types, I opened the data table and sure enough I saw that every field was surrounded by quotation marks {"} as a text qualifier. THAT was the problem! Switched over the design view and changed the field type and sure enough that did the trick. ArcMap honors Access field specifications and we were able to view the event class in no time. Took a bit more patience waiting while we exported the shapefile, but it was nice to see the completion of what should have been a routine process.

Why were there quotation text qualifiers around each field? Well, the student told me the file was created using Excel 2007, which I have not yet used. Perhaps this is standard procedure for Excel 2007? If not, perhaps there is some setting in Excel that will inadvertently place text qualifiers around fields?

Repeating from above: The conclusion is that the manipulation of large tables is often times best done using Microsoft Access.

Wednesday, October 03, 2007

[updated 10/05 to include links to free dissertation abstracts and 24-page previews, compliments of UMI Dissertation Publishing at ProQuest. See comments for more info. Thanks Mike!]

Here's the latest installment of GIS-related dissertations that have caught my eye. Previous lists include 11/05, 01/06, 01/06, 04/06, 07/06, 10/06, 04/07. (Of course, this is not a comprehensive list...only those I find interesting.)

"The research consisted of three parts: One, the quantitative aspect of the research was completed through a two-part questionnaire in which 204 students attending a high school in Northwest Arkansas responded. The first part contained questions concerning demographic information; the second part contained a 5-point Likert scale to measure their attitudes towards using/learning GIS. Descriptive statistics, Independent t-test, One-Way ANOVA, and tests of between group effects (Two-Way ANOVA) were used to analyze the data collected. The third part contained GIS use information."

"This dissertation showed that county averages of the incidence of lung cancer, chronic bronchitis, and chronic pneumonia are well correlated. Also, the dissertation showed that aeroradioactivity can be used to locate geological areas with higher soil radioactivity and areas with higher indoor radon."

"This project explores a new approach of blending qualitative research with GIS by creating two software-level strategies. The first strategy is to include qualitative data directly into a GIS database from the beginning of research, thereby aiding in the comprehensive analysis of multiple forms of data... The second strategy meshes GIS with CAQDAS (Computer-Aided Qualitative Data Analysis Software), specifically the ATLAS ti ® program."

"Findings: Nursing homes in counties with smaller HHI or closer to competitors have more staffing hours, fewer deficiencies, higher quality measure scores and higher total scores. Predicted average occupancy of other nursing homes in the county is not significantly related with quality in general, the reason may be that it does not have sufficient variation."

"This thesis examines the spatially uneven evolution of the Internet industry in China's changing socio-economic environment. Using a census data, I demonstrate the evolution of founder structures and business models of China's Internet startups in space and through time. Taking a system view of institutions and a resource-based view of industrial development, I interpret the decade-long history of China's Internet development, characterized by the interplay of multiple factors at multiple geographic scales, through an analytic narrative."

"In this dissertation, we propose a new index structure, termed VoR-tree , that incorporates Voronoi diagrams into the R-tree index structure for I/O-optimal processing of nearest neighbor queries on point datasets. The neighborhood information encoded in Voronoi diagrams allows a VoR-tree-based algorithm to optimally explore the data space towards the result."

"In this dissertation we propose and evaluate a Service Oriented Architecture for seamless coupling of real-time and non-real time geographic data with scientific geospatial applications. We describe necessary principles and service features for accessing both data types and outline Data Grid architecture to address these requirements. We describe various methods for improving the performance of our Web Services such as adoption of Binary XML Frameworks and integration of a message oriented middleware for streaming the responses. We introduce a novel approach to map Geography Markup Language (GML) based XML queries to relational database queries."

"The use of satellite technology by military planners has a relatively long history as a tool of warfare, but little research has used satellite technology to study the effects of war. This research addresses this gap by applying satellite remote sensing imagery to study the effects of war on land-use/land-cover change in northeast Bosnia."

"This is a work of historical geography examining the role of an Indian-origin transportation route in the development of the colonial settlement system that emerged in the North Carolina Piedmont during the mid 18 th century. This system has evolved in modern times into an important polycentric urban region, and the area's current inhabitants attribute this pattern to the Indian route, the Indian Trading Path. The relationship between the route and settlement development has not previously been tested, however."

About Me

Father of two boys, married to an engineering student, work as a GIS librarian & adjunct professor, love sci-fi/fantasy (especially Gene Wolfe, Rudy Rucker, Jeff Noon, Frank Herbert), table tennis, and a follower of the specific carbohydrate diet since 11/2005; vegan since 07/2006; faltered in the first half of 2008 but am working hard to get back on track.